1. Technical Field
The present invention relates in general to an improved burnishing slider and, in particular, to an improved system, method, and apparatus for burnishing very small asperities and cleaning the loose particles adhering to magnetic recording media.
2. Description of the Related Art
Data access and storage systems typically comprise one or more storage devices that store data on magnetic or optical storage media. For example, a magnetic storage device is known as a direct access storage device (DASD) or a hard disk drive (HDD) and includes one or more disks and a disk controller to manage local operations concerning the disks. The hard disks themselves are usually made of aluminum alloy or a mixture of glass and ceramic, and are covered with a magnetic coating. Typically, one to five disks are stacked vertically on a common spindle that is turned by a disk drive motor at several thousand revolutions per minute. Hard disk drives have several different typical standard sizes or formats, including server, desktop, mobile, and microdrive.
A typical HDD also utilizes an actuator assembly. The actuator moves magnetic read/write heads to the desired location on the rotating disk so as to write information to or read data from that location. Within most HDDs, the magnetic read/write head is mounted on a slider. A slider generally serves to mechanically support the head and any electrical connections between the head and the rest of the disk drive system. The slider is aerodynamically shaped to glide over moving air in order to maintain a uniform distance from the surface of the rotating disk, thereby preventing the head from undesirably contacting the disk.
Typically, a slider is formed with an aerodynamic pattern of protrusions on its air bearing surface (ABS) that enables the slider to fly at a constant height close to the disk during operation of the disk drive. A slider is associated with each side of each disk and flies just over the disk's surface. Each slider is mounted on a suspension to form a head gimbal assembly (HGA). The HGA is then attached to a semi-rigid actuator arm that supports the entire head flying unit. Several semi-rigid arms may be combined to form a single movable unit having either a linear bearing or a rotary pivotal bearing system.
As the recording density of storage media increases, the substrates for media disks are getting smoother. The media disks typically have magnetic structures, lubricant layers, and an overcoat, all of which are all getting thinner with respect to the prior art. The qualification glide height is decreasing but fly heights are also decreasing to below 10 nm. It becomes very important for the reliability of the media that the disks are burnished effectively and that all the loose particles, ranging from approximately 10 nm to 500 nm, are removed from the surface along with the asperities.
In the past, there have been burnish slider designs having waffle, triangular, and diamond shape air bearing features that were designed to be in contact with the disk and burnish the asperities. There also have been traditional, two-rail slider designs that are effective in removing loose particles. The waffle, triangular, and diamond pad burnish slider designs were suitable for disks with high roughness. However, for very smooth disks, the contact force applied by these designs is very high and can cause damage to the disks. Two-rail slider designs are very efficient in removing larger particles but they cannot effectively burnish smaller asperities. All the above-mentioned sliders were fabricated by traditional machining processes. Machining is less desirable due to loose tolerances inherent in the process, and due to the generation of machined particles that can cause contamination problems.
Recently, some manufacturers have started utilizing a reactive ion etching (RIE) process. This category includes sliders with oval pads, oval and rectangular channel-like designs, and hybrid burnish head designs. The oval pad designs were found to be unstable in the contact mode. The hybrid slider design concept does not address the magnitude or the control of the contact forces. Thus, an improved air bearing burnish slider that can both burnish very small asperities and clean the loose particles adhering to magnetic recording media would be desirable.